The truth of it was he had opted out of life. He'd decided his computer and bedroom were safe and the world outside it was too much for him. He had a couple of rejections (one from a job and one from a girl) in a short space of time and it came at a time where he was figuring out who he was, so it felt like the world was rejecting him iyswim. He struggled socially because he'd talk to people the same way he would post on Reddit etc so he came across awkward and weird.
This is eerily familiar.
Unfortunately the story in my family didn't go the same way. They swallowed it whole and didn't think there was any other explanation.
Tbh, though I'm not sure that if my parents had acted differently, it would have stopped him. My brother had been 'prepped' by those around him to expect a certain negative reaction. The ultra defensiveness manifested as aggression and certain questions had been already been framed as being totally off limits, or 'transphobia'.
DH was labelled as transphobic BEFORE we even knew. This put me in an position which effectively was trying to drive a wedge between me and my husband. I didn't take that well. Ultimately that was the straw that broke my back. I was supposed to accept my brother and his partner, but they had rejected my husband. My parents, sided with my brother because he was 'fragile' and excused appalling behaviour by both him and his partner. DH and I literally didn't do or say anything.
My parents tried to keep the peace and stay on side with both of us. That meant pretty much not talking about my brother in my presence.
My Dad was particularly strangely silent. He never has really said much. He once commented that my brother was considering being a teacher and did I think it was a good idea given he was trans. It was clear he had doubts and concerned, but I didn't want to be honest about what I thought about it. It was another opting out of 'real life' to remain in the 'safe' environment of education. DS had already failed one degree and then did another degree - all of which my parents had funded fully. (I'd worked my way through university).
I think in a way, there is very little you can do as a sister. You can try and guide your parents and support them, but you as a sister are almost seen as a threat and 'competition' to them. You are the daughter - and you remind them that they are not.
I felt it was more of a 'cuckoo type' attitude. I was forced out of the family and replaced as the daughter. I can't explain it in other terms.
In the end for all the talk of the trans person being rejected by their family, I felt that it was ultimately me who was.
I tried to be supportive, but the behaviour and the aggression was the problem. It was being told that my childhood memories were 'wrong' and my brothers were the one that were somehow right. It was me who had to do all the compromising and tolerance and none of this was extended to me. I was never given time to absorb it or have any feelings of my own. It was all about my brother needing the attention and being prioritised.
Maybe trans is real. But every time I read stories and compare notes with others in a similar position the same pattern of needing attention, having a certain background, often with a history of bullying thrown in too and having similar interests pops up again and again.
I do think there is a huge cultural thing going on. I think that the denial that people who say they are trans have underlying issues, is a huge part of the problem. The trans thing is an easy way to deflect facing up to these issues which they need to do regardless of their gender identity.
Good luck. You'll have a rocky road whatever happens.
My advice would generally be to know when to stay out of things rather than getting sucked into the drama. You have other priorities. Don't forget that and that YOU matter too.